RANDOLPH — In one of his more confrontational speeches this campaign season, Scott Brown on Tuesday accused his Democratic opponent Elizabeth Warren of seeking to impose $3.4 trillion in new taxes over the next decade in “the largest tax hike since World War II.”

The remarks, delivered to the South Shore Chamber of Commerce at Lombardo’s in Randolph, were billed as a major policy speech, but did not make any new policy pronouncements, instead reiterating themes that Brown has struck throughout his Senate race.

He emphasized his bipartisan approach to politics, promised never to “demonize you as our job creators,” and blasted Warren, a Harvard Law School professor, calling her philosophy on taxes “a dangerous one.”

“Professor Warren sees things differently,” he told the crowd of 500. “To her, there’s no bad time to raise a tax.”

“This is a made-up number,” she said during a campaign stop in Quincy. “The interesting question is why right now. I think Scott Brown is very worried about this race, and the reason I think he’s worried is that when Mitt Romney picked Paul Ryan as his running mate, the economic issues clicked into place with perfect clarity. And that is, protect those at the top – give them every loophole, give them every break and make everyone under them pay for it.”

For Brown, the speech was an opportunity to try to change the conversation, putting pressure back on his opponent’s tax positions. Since Representative Paul Ryan, of Wisconsin, was chosen over the weekend as Romney’s running mate, Warren and other Democrats have tried to link Brown to Ryan, whose conservative budget proposal is expected to be less popular in Massachusetts than in other states.

Brown voted to block the Ryan budget twice, citing its cuts to Medicare, but has not been as specific about whether he supports other elements of the plan. On Tuesday, he did not take questions from the chamber audience or the press, walking out the back door with a cellphone on his ear as he was chased by reporters and promising to answer questions Wednesday.

Democrats mocked Brown for eluding the press and Warren made a point of holding two extended question-and-answer sessions with reporters, one for 11 minutes and a second one for 15 minutes.

“He’s out and visible without having to talk about the issues or take any questions, because when he talks about the issues, he’s got a real problem,” Warren said. “And when he starts to take questions, he’s got a bigger problem.”

Still, not all of Warren’s answers were detailed. She said she would need time to evaluate President Obama’s budget plan before saying whether she supports it. The budget, which the Senate rejected 99-0 in May, was proposed in February.

In his speech, Brown mocked Warren for declining to pay a voluntarily higher tax rate, even as she is in favor of raising taxes on others, calling it “one box she declined to check.” The comment drew a few chuckles from those in the audience who knew it was a reference to the controversy over Warren’s undocumented claims to Cherokee Heritage, which have drawn accusations that she “checked boxes” to advance her academic career.

He also criticized Warren for pressing to end the Bush tax cuts for upper income earners, those who earn $250,000 a year.

“Only in Washington, D.C. and the faculty lounge at Harvard does keeping tax rates where they are represent a tax cut,” he said. “Let me give you a little straight talk: when tax rates go up, that’s a tax hike any way you slice it. And that’s exactly what Professor Warren wants.”

Brown also warned of the so-called “fiscal cliff,” which he also labeled “Taxmageddon” – a reference to the potential for tax hikes and cuts in government programs come January 1.

“It’s even more urgent right now that we stop from not only approaching but going over that fiscal cliff on January first,” he said. “Whatever it takes.”

“I’ve made this known to my leader and anyone who will listen down there,” he added. “Is it a special session of Congress that we need to do this summer? So be it. Is it we need to get to business right away when we get back off break? Then so be it. Do we need to battle through the lame duck session and get it done and work together? Then so be it.”

Democrats dispute Brown’s characterization of Warren’s position on taxes.

The biggest difference of opinion is over a change in Social Security taxes worth $1 trillion over 10 years, an issue in which Warren appears to have dialed back her position. Warren told an audience in November 2011 that such a tax increase would solve long-term problems with Social Security funding.

Her campaign has since said she was offering a hypothetical proposal, and that is not her current position.

She continues, however, to advocate for multiple tax hikes on the oil industry, upper-income earners, and and carried interest.

For example, Warren has said she would end the Bush tax cuts for those earning $250,000 a year, which would amount to an increase of $848.8 billion over the next decade.

Brown alluded to his difference with Warren on that issue, and the definition of wealth itself, in his speech Tuesday, saying that “many have two incomes and they work hard and they find themselves being called rich by politicians and professors.”

Brown also hit Warren for supporting President Obama’s health care law, which he credits with $675 billion in added taxes over the next decade, including penalties that the US Supreme Court labeled as “taxes” in upholding the law earlier this summer.

Brown opposes the law. Democrats said in a briefing paper yesterday that the health care law would provide tax credits to 19 million people to help them afford insurance and would provide $40 billion in tax credits to small business to help provide employee health plans.

Noah Bierman can be reached at nbierman@globe.com. Follow him on Twitter @nbierman.